The present invention relates to a circuit arrangement for compensating for the temperature dependence of the sensitivity and the null point of a piezoresistive pressure sensor in a bridge circuit having an auxiliary amplifier which is arranged thermally coupled to the pressure sensor and is connected to the latter, and in the output circuit of which the feed diagonal of the pressure sensor is connected, as well as having an output amplifier which is connected to the output diagonal of the pressure sensor, and to the input of which a temperature dependent correction voltage can be applied via a resistor arrangement.
In a known circuit arrangement of this type ("Elektronik" 13/June 29, 1984, pages 95-98), a temperature sensor connected in series with a resistor forms a temperature feeler, to the output of which the input of an operational amplifier is connected. On the output side, the operational amplifier acts on a transistor which serves as a control element (chopper) and into the emitter-collector circuit of which the feed diagonal of the pressure sensor is connected in a bridge circuit; in this manner, a temperature-controlled voltage supply for the pressure sensor is made available, by which the temperature dependence of the sensitivity of the pressure sensor is compensated. For compensating for the temperature dependence of the null point of the pressure sensor in the known circuit arrangement, a resistor arrangement is provided which is connected on the one hand via resistors to one input of an output amplifier connected to the output diagonal of the pressure sensor and, on the other hand, to a fixed reference voltage; the reference potential of the output amplifier is made available by means of a further operational amplifier which is connected on the input side parallel to the feed diagonal of the pressure sensor, so that the compensation of the temperature behavior of the null point of the pressure sensor depends, in the known circuit arrangement, on the magnitude of the voltage at the feed diagonal of the pressure sensor.